package com.hmdp.utils;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import lombok.extern.slf4j.Slf4j;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Component;

import java.time.LocalDateTime;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.function.Function;

@Component
@Slf4j
public class CacheClient {

    private final StringRedisTemplate stringRedisTemplate;

    public CacheClient(StringRedisTemplate stringRedisTemplate) {
        this.stringRedisTemplate = stringRedisTemplate;
    }

    public void set(String key, Object value, Long time, TimeUnit timeUnit){
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(value),time,timeUnit);
    }


    public <R,ID>R shopWithPassThrough(String keyPrefix, ID id, Class<R> type, Function<ID,R>dbFallback,Long time,TimeUnit unit){
        //缓存穿透
        String key= keyPrefix+id;
        String string = stringRedisTemplate.opsForValue().get(key);
        if(StrUtil.isNotBlank(string)){
            return JSONUtil.toBean(string, type);
        }

        if(string!=null){
            return null;
        }

        R r= dbFallback.apply(id);

        if(r==null){
            stringRedisTemplate.opsForValue().set(key,"",RedisConstants.CACHE_NULL_TTL, TimeUnit.MINUTES);
            return null;
        }

        String jsonStr = JSONUtil.toJsonStr(r);
        this.set(key,r,time,unit);

        return r;
    }


    private boolean tryLock(String key){
        Boolean b = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(b);
    }

    private void unLock(String key){
        stringRedisTemplate.delete(key);
    }


    private static final ExecutorService CACHE_REBUILD_EXECUTOR = Executors.newFixedThreadPool(10);
    /**
     * 逻辑过期解决缓存击穿
     */
    public <R,ID>R shopWithLogicalExpire(String keyPrefix, ID id, Class<R> type,  Function<ID,R>dbFallback,Long time,TimeUnit unit) throws InterruptedException {
        String key= keyPrefix+id;
        String string = stringRedisTemplate.opsForValue().get(key);
        if(StrUtil.isBlank(string)){
            return null;
        }

        RedisData redisData = JSONUtil.toBean(string, RedisData.class);
        R r = JSONUtil.toBean((JSONObject) redisData.getData(), type);
        LocalDateTime expireTime = redisData.getExpireTime();

        if(expireTime.isAfter(LocalDateTime.now())){
            return r;
        }

        String lockKey=RedisConstants.LOCK_SHOP_KEY+id;
        boolean isLock = tryLock(lockKey);
        if(isLock){
            CACHE_REBUILD_EXECUTOR.submit(()->{
                try {
                    R r1 = dbFallback.apply(id);
                    setWithLogicalExpire(key,r1,time,unit);
                } catch (Exception e) {
                    throw new RuntimeException(e);
                } finally {
                    unLock(lockKey);
                }

            });
        }

        return r;
    }

    public void setWithLogicalExpire(String key,Object value,Long time,TimeUnit unit){
        RedisData redisData = new RedisData();
        redisData.setData(value);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(unit.toSeconds(time)));

        stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(redisData));
    }

}
